Control apparatus of multiple ship propellers

ABSTRACT

A control apparatus controls multiple outboard motors transmitting and receiving operation information mutually via a communication line and is configured to give a thrust difference between the outboard motors in the event of a fault of an electric rudder tilter used to turn a ship by turning a rudder by controlling thrusts of the outboard motors according to a detection value of a steering angle sensor detecting a steering angle. When a ship sailing direction is controlled by the thrust difference, the control apparatus controls the outboard motors by using a steering angle threshold up to which the thrust difference is not given between the outboard motors in a region where a steering angle is small, and in a case where the steering angle exceeds the steering angle threshold, by using a predetermined value of the thrust difference with which the thrust difference is given between the outboard motors.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control apparatus of multiple ship propellers that controls plural ship propellers, such as outboard motors and inboard motors.

2. Related Art

There is a steering device of an outboard motor generating steering power using an electrical motor in the related art. For example, Japanese Patent No. 2959044 (Patent Document 1) discloses an electrical steering device that generates steering power to steer an outboard motor main body by detecting a rotation angle and a rotation direction of a steering wheel using a sensor and controlling rotations of an electrical motor according to the detected value using a controller.

Also, for example, JP-A-2007-91115 (Patent Document 2) discloses a technique for a control apparatus in a ship of a multi-outboard motor type equipped with plural outboard motors. This ship includes a handle, a steering angle sensor detecting a steering angle of the handle, plural outboard motors attached to the transom, electrical rudder tilters connected to the respective outboard motors, and a control apparatus controlling outputs from the respective outboard motors. With the technique disclosed herein, the control apparatus controls a thrust and a direction of the outboard motors as a whole by regulating outputs, trim angles, or heights of propellers of the respective outboard motors according to the steering angle and a sailing condition of the ship.

A ship of a multi-outboard motor type equipped with more than one, for example, two outboard motors may have the whine in some cases because of a slight difference between the right and left engine speeds. In order to prevent this inconvenience, for example, JP-A-5-86894 (Patent Document 3) discloses a rotation phase control apparatus of an engine for two outboard motors on the right and left each incorporating an engine. This control apparatus reduces vibrations of the hull by cancelling out vibrations of the engines on the right and left.

Patent Document 1: Japanese Patent No. 2959044 (Claims and FIG. 3)

Patent Document 2: JP-A-2007-91115 (Abstract and FIG. 1)

Patent Document 3: JP-A-5-86894 (paragraphs [0015] to [0022], FIG. 2, and FIG. 3)

The steering device of an outboard motor disclosed in Patent Document 1, however, has a problem that a rudder cannot be moved in the event of a fault of the electrical steering device and a ship operator becomes unable to turn the ship as he intended.

Also, the ship operator cannot turn the ship of a multi-outboard motor type disclosed in Patent Document 2 as he intended when it becomes impossible to turn the rudder in one outboard motor in the event of a fault of the electric rudder tilter while the ship is driven by multiple outboard motors. More specifically, in a case where it becomes impossible to turn the rudder in one outboard motor when the rudder is positioned substantially straight, although the intact rudder in the other outboard motor can be turned outward, the ship operator can turn the ship only in one direction. In a case where it becomes impossible to turn the rudder in one outboard motor when the rudder is positioned inward, it is highly likely that the rudder in the failed outboard motor gets in the way and makes it also impossible to turn the rudder in the other outboard motor although the electrical rudder tilter thereof has no trouble. Further, should a fault occur in all the electrical rudder tilters, there arises a problem that the ship operator cannot change a turning direction of the ship at all. Also, there is still another problem that because a thrust difference between the outboard motors is small when an operation angle is small, the whine occurs due to a slight difference between the right and left engine speeds.

Also, it is described that the rotation phase control apparatus of an engine disclosed in Patent Document 3 prevents the occurrence of the whine by cancelling out vibrations of the engines on the right and left. This technique, however, is different from a technique of preventing the occurrence of the whine itself generated in the outboard motors. Moreover, the electrical rudder tilter is not disclosed in this reference.

SUMMARY OF THE INVENTION

The invention is devised to solve the problems discussed above and has an object to provide a control apparatus of multiple ship propellers enabling a ship operator to turn a ship by merely operating a steering device without having to go through complicated operations on an accelerator lever even when the ship operator becomes unable to move a rudder in the event of a fault of an electrical rudder tilter while the ship is driven by multiple ship propellers.

A control apparatus of multiple ship propellers according to an aspect of the invention is a control apparatus of multiple ship propellers that controls operation states of at least two ship propellers attached to a transom and transmitting and receiving operation information of the respective ship propellers mutually via a communication member, and is configured to give a thrust difference between the ship propellers in the event of a fault of an electric rudder tilter used to turn a ship by turning a rudder by controlling thrusts of the respective ship propellers according to a detection value of a steering angle detector that detects a steering angle. When a sailing direction of the ship is controlled by the thrust difference, the control apparatus controls the respective ship propellers by using a steering angle threshold up to which the thrust difference is not given between the ship propellers in a region in which the steering angle is small, and in a case where the steering angle exceeds the steering angle threshold, by using a predetermined value of the thrust difference with which the thrust difference is given between the ship propellers.

When configured as above, it becomes possible to give a thrust difference between the ship propellers (outboard motors) by merely operating the steering device in the event of a fault of the electric rudder tilter. Hence, it is no longer necessary to generate thrusts of the respective ship propellers to turn the ship by operating an accelerator lever when it becomes impossible to move the rudder. The ship operator thus becomes able to turn the ship by merely operating the steering device without having to go through complicated operations on the accelerator lever.

The foregoing and other object, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a system configuration and used to describe a control apparatus of multiple ship propellers according to a first embodiment of the invention;

FIG. 2 is a flowchart depicting an operation of turn control by the control apparatus of multiple ship propellers according to the first embodiment of the invention;

FIG. 3 is a view used to describe a first method of steering determination processing by the control apparatus of multiple ship propellers according to the first embodiment of the invention;

FIG. 4 is a flowchart depicting a second method of steering determination processing by the control apparatus of multiple ship propellers according to the first embodiment of the invention;

FIG. 5 is a view used to describe the second method of steering determination processing by the control apparatus of multiple ship propellers according to the first embodiment of the invention;

FIG. 6 is a flowchart depicting a first method of thrust difference control by the control apparatus of multiple ship propellers according to the first embodiment of the invention; and

FIG. 7 is a flowchart depicting a second method of thrust difference control by the control apparatus of multiple ship propellers according to the first embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a preferred embodiment of a control apparatus of multiple ship propellers of the invention will be described with reference to the accompanying drawings. It should be appreciated, however, that the invention is not limited to the embodiment below and various changes in design are included in the invention.

First Embodiment

FIG. 1 is a view showing a system configuration and used to describe a control apparatus of multiple ship propellers of a first embodiment. Referring to FIG. 1, numeral 1 denotes a ship equipped with multiple outboard motors (hereinafter, referred to simply as the ship). The ship 1 includes a handle 2 installed at a driver's seat, a steering angle sensor 3 detecting a steering angle of the handle 2, a ship handling seat controller 4 computing a thrust difference according to a steering angle, ship propellers (hereinafter, referred to as the outboard motors) 5 a and 5 b as motive power sources, engine controllers 6 a and 6 b controlling engines by ignition and jetting, and electric rudder tilters 7 a and 7 b turning rudders using actuators. The ship handling seat controller 4, the engine controllers 6 a and 6 b, and the electric rudder tilters 7 a and 7 b are interconnected via communication lines 8, such as CAN lines.

The ship handling seat controller 4 and the engine controllers 6 a and 6 b form the control apparatus of the multiple outboard motors. Although these components are provided separately in the illustration of FIG. 1, these components may be formed integrally as long as all the functions furnished to each are achieved. Further, the electric rudder tilters 7 a and 7 b are not necessarily provided to the outboard motors 5 a and 5 b in a one-to-one correspondence, and one electric rudder tilter 7 a or 7 b may be provided for the two outboard motors 5 a and 5 b.

A ship incorporating the control apparatus of the multiple outboard motors of the first embodiment is configured as above. An operation of the control apparatus of multiple outboard motors will now be described. An operation of the control apparatus of multiple outboard motors of the first embodiment is divided to two steps: steering determination processing and engine thrust difference control. The steering determination processing is to determine a thrust difference to be given between the outboard motors according to the steering angle. The engine thrust difference control is to control engine speeds of the respective outboard motors according to the determined thrust difference.

Firstly, an operation of turn control in the event of a fault of the electric rudder tilters 7 a and 7 b will be described in accordance with the flowchart of FIG. 2.

Referring to FIG. 2, when the ship operator moves the handle 2 in Step S201, the ship handling seat controller 4 receives a signal from the steering angle sensor 3 that detected a steering angle of the handle 2. In Step S202, a thrust difference is determined according to the steering angle. Thereafter, in Step S203, thrusts (engine speed or the like) of the respective outboard motors 5 a and 5 b are controlled according to the thrust difference. In other words, the ship handling seat controller 4 serves as a steering determination processing portion and an engine thrust difference control portion.

In a case where a thrust difference is given between the engines (outboard motors 5 a and 5 b), the ship handling seat controller 4 computes a throttle opening (the position of an accelerator lever that regulates a throttle opening) using a value predetermined for a thrust variation and sends the computation result to the engine controllers 6 a and 6 b. Alternatively, a thrust difference may be given between the outboard motors 5 a and 5 b in such a manner that the ship handling seat controller 4 determines a thrust difference and sends a thrust variation to the respective engine controllers 6 a and 6 b while the engine controllers 6 a and 6 b feed back the thrusts to the handling seat controller 4. In the former case, because the ship handling seat controller 4 carries out all the computations, a function is merely added to the ship handling seat controller 4, which is a normal ship device. In the latter case, because the engine controllers 6 a and 6 b perform the feedback control, there is an advantage that the precise control is performed more easily.

Methods of the steering determination processing in Step S202 will now be described.

A first method of the steering determination processing in Step S202 of FIG. 2 will be described on the basis of the graph of FIG. 3. Herein, assume that a rightward command for a steering angle variation is positive and a leftward command is negative. Also, in a case where there are two outboard motors 5 a and 5 b, assume that a thrust difference is a value obtained by subtracting a thrust of the starboard motor from a thrust of the portside motor. More specifically, when a thrust difference is positive, thrusts establish a relation, portside motor>starboard motor, whereas when a thrust difference is negative, thrusts establish a relation, portside motor<starboard motor. Further, assume that the handle 2 is a free handle and the handle 2 has no center point.

An engine thrust difference is determined according to the magnitude of a steering angle variation by an operation on the handle 2 by the ship operator. Referring to FIG. 3, when a steering angle variation falls within a range from thresholds −A1 to A1, no engine thrust difference is given between the outboard motors 5 a and 5 b. This configuration is adopted for the purpose of providing a play for safe sailing by neglecting fine motion of the handle 2 and also for the purpose of preventing the occurrence of the whine. Because the whine occurs when the engine speeds of the outboard motors 5 a and 5 b differ slightly, a thrust difference such that exceeds a region in which the whine is likely to occur is given between the outboard motors 5 a and 5 b. It should be noted, however, that a thrust difference in this instance is of the magnitude small enough not to provide a feeling of strangeness to the ship operator. In a case where a steering angle variation is smaller than the threshold −A1 or larger than the threshold A1, engine thrust difference control is performed and the magnitude of a thrust difference is determined according to the magnitude of the steering angle variation. Further, when a steering angle variation is smaller than a threshold −A2 or larger than a threshold A2, a thrust difference clipped at a predetermined value is given between the outboard motors 5 a and 5 b to prevent a thrust difference from increasing abruptly. The thrust difference thus determined is a value corresponding to a steering angle variation in a predetermined period, and therefore the thrust difference is accumulated.

A second method of the steering determination processing in Step S202 of FIG. 2 will now be described in accordance with the flowchart of FIG. 4 and on the basis of the graph of FIG. 5.

According to the second method of the steering determination processing, a thrust difference for a steering angle variation in a direction to decrease a thrust difference is made larger than a thrust difference for a steering angle variation in a direction to increase a thrust difference. For the control in the direction to increase a thrust difference, a map a indicated by a solid line in FIG. 5 is used, and a map b indicated by a broken line in FIG. 5 is used for the control in the direction to decrease a thrust difference. Herein, as with the first method above, assume that a rightward command for a steering angle variation is positive and a leftward command is negative. Also, in a case where there are two outboard motors 5 a and 5 b, assume that a thrust difference is a value obtained by subtracting a thrust of the starboard motor from a thrust of the portside motor.

In Step S401 of FIG. 4, whether the thrust difference control is being performed is determined. When the thrust difference control is not being performed, the thrust difference is 0. Then, because the command is a command for the control in the direction to increase a thrust difference, a thrust difference is determined in Step S402 from the map a of FIG. 5. A method of determining a thrust difference from the map a is the same as the first method above.

In a case where it is determined in Step S401 that the thrust difference control is being performed, the flow proceeds to Step S403 in which whether the command is a command for an operation in a direction in which a steering angle variation decreases an accumulated thrust difference is determined. When the sign of a steering angle variation and the sign of an accumulated thrust difference are the same, the command is a command for an operation in a direction to increase the accumulated thrust difference. Hence, the flow proceeds to Step S402 and a thrust difference is determined using the map a. For example, when an accumulated thrust difference before the command is positive, the ship 1 is in a state where a thrust of the portside motor is larger than a thrust of the starboard motor. In this state, a steering angle variation takes a positive value when the ship operator turns the handle 2 rightward. In other words, when the sings of an accumulated thrust difference and a steering angle variation are the same, the command is a command for an operation in the direction to increase the accumulated thrust difference.

When the sign of a steering angle variation and the sign of an accumulated thrust difference are opposite, the command is a command for an operation in a direction to decrease the accumulated thrust difference. Hence, the flow proceeds to Step S404. For example, when an accumulated thrust difference before the command is positive, the ship 1 is in a state where a thrust of the portside motor is larger than a thrust of the starboard motor. In this state, a steering angle variation takes a negative value when the ship operator turns the handle 2 leftward. In other words, when the signs of an accumulated thrust difference and a steering angle variation are opposite, the command is a command for an operation in the direction to decrease the accumulated thrust difference.

In Step S404, a thrust difference is determined according to the steering angle variation from the map b shown in FIG. 5. In comparison with the map a, thresholds of steering angle variation up to which no thrust difference is given between the outboard motors 5 a and 5 b are small (B<A) in the map b. Also, an inclination is larger in the map b than in the map a. In other words, the control to eliminate an accumulated thrust difference using the map b makes the ship more responsive than by the control to increase an accumulated thrust difference using the map a.

After the thrust difference is determined in Step S404 according to the steering angle variation, whether the positive or negative sign of the accumulated thrust difference is different from the sign of the last value is determined in Step S405. In a case where the signs are different, a value of the thrust difference is determined so that the accumulated thrust difference becomes 0 in Step S406. In order to prevent a thrust difference determined from the map b used for the control to decrease an accumulated thrust difference from being used for the control in the direction to increase an accumulated thrust difference, the thrust difference is clipped at 0 when an accumulated thrust difference changes from negative to positive and vice versa.

A first method of the engine thrust difference control in Step S203 of FIG. 2 will now be described in accordance with the flowchart of FIG. 6. This method of the engine thrust difference control is a method of controlling a thrust difference so that a total thrust of all the outboard motors 5 a and 5 b does not change before and after the thrust difference control.

Referring to FIG. 6, in the engine thrust difference control, whether the thrust difference computed in Step S202 of FIG. 2 is not 0 is confirmed first in Step S601. When the thrust difference is 0, the flow ends because there is no need for the thrust difference control.

When the thrust difference is other than 0, whether the thrust difference is positive or negative is confirmed in Step S602. When the thrust difference is positive, a thrust of the portside motor is increased and a thrust of the starboard motor is decreased. Conversely, when the thrust difference is negative, a thrust of the portside motor is decreased and a thrust of the starboard motor is increased. For example, in a case where a thrust of the outermost outboard motor is changed, the control to increase a thrust of the portside motor by half the value of the trust difference and to decrease a thrust of the starboard motor by half the value of the thrust difference is performed so that a total thrust of all the outboard motors does not change. In a case where there are four or more outboard motors and a thrust of the inner outboard motor is changed, the ship can be turned efficiently by making a thrust difference equal to or smaller than a. thrust of the outermost outboard motor. In a case where an odd number of outboard motors are mounted to the ship, the outboard motor in the center may not be taken into account regarding a thrust difference because this outboard motor has little influence when the ship is turned. A thrust is changed by regulating a throttle opening or an amount of fuel.

After thrusts are changed in Step S603 and Step S604, thrust upper and lower limits clip processing is performed in Step S605. This processing prevents overheating caused by exceedingly increasing a thrust or prevents an engine stall caused by exceedingly decreasing a thrust. In a case where a thrust is clipped, the thrust can no longer be changed over the limit. However, by decreasing a thrust of the other outboard motor when the thrust is clipped at the upper limit and by increasing a thrust of the other outboard motor when a thrust is clipped at the lower limit, the thrust difference determined in Step S202 can be given between the outboard motors 5 a and 5 b. It thus becomes possible to turn the ship smoothly.

A second method of the engine thrust difference control in Step S203 of FIG. 2 will now be described in accordance with the flowchart of FIG. 7. By this method of the engine thrust difference control, in a case where the thrust difference control is performed, the control to increase only a thrust that is not under the thrust difference control is performed. Because a thrust that is not under the thrust difference control is not decreased, the ship can be turned smoothly.

Referring to FIG. 7, the processing in Step S701 and Step S702 is the same, respectively, as Step S601 and Step S602 of FIG. 6 in the first method. In Step S701, whether the thrust difference is not 0 is determined and whether the value of the thrust difference is positive or negative is determined in Step S702. In a case where it is determined in Step S702 that the value of the thrust difference is positive, a thrust of the portside motor is increased by only the value of the thrust difference in Step S703. In a case where it is determined in Step S702 that the value of the thrust difference is negative, a thrust of the starboard motor is increased by only the value of the thrust difference in Step S704. In Step S705, a thrust is clipped at the upper limit to prevent overheat of the engine. In a case where the thrust is clipped at the upper limit, a thrust of the other outboard motor may be decreased. Alternatively, because the ship is in a failure mode after all, the upper limit may be set at the maximum thrust when the ship sails straight ahead in order to secure a region in which a thrust difference is given between the outboard motors 5 a and 5 b.

As has been described above, according to the control apparatus of multiple ship propellers of the first embodiment, a thrust difference can be given between the outboard motors 5 a and 5 b by an operation on the handle 2 in the event of a fault of the electric rudder tilter 7 a and 7 b. Hence, it is no longer necessary to generate thrusts of the respective outboard motors 5 a and 5 b by an operation on the accelerator lever in order to turn the ship when it becomes impossible to move the rudders. Hence, the ship operator becomes able to turn the ship by merely operating the handle 2 without having to go through complicated operations on the acceleration lever.

Also, it becomes possible to prevent the whine by giving a predetermined or larger thrust difference by avoiding an operation region in which a fine thrust difference such that causes the whine is given between the outboard motors.

For the control in the direction to decrease a thrust difference in the presence of thrust difference, a larger thrust difference for the steering angle is given between the outboard motors than by the control in the direction to increase a thrust difference in the absence of thrust difference. Hence, the ship operator becomes able to quickly return the ship to a state where there is no thrust difference. The ship thus becomes easier to handle for the ship operator and sails safely.

Also, the ship is allowed to sail safely by controlling a total thrust of all the outboard motors in the absence of a thrust difference between the outboard motors 5 a and 5 b and a total thrust of all the outboard motors when a. thrust difference is given between the outboard motors 5 a and 5 b to take the same value.

Also, ship responsivity can be obtained by configuring in such a manner that in a. case where a thrust difference is given between the outboard motors 5 a and 5 b in a state where no thrust difference has been given between the outboard motors 5 a and 5 b, either the outboard motor a or the outboard motor b whose thrust is to be changed is controlled only in a direction to increase the thrust, and in a case where a thrust difference is eliminated after the thrust difference is given between the outboard motors 5 a and 5 b, a thrust of the outboard motor a or the outboard motor b whose thrust is increased is controlled to decrease the thrust only to the thrust before the thrust difference is given between the outboard motors 5 a and 5 b or to a thrust of an outboard motor having the smallest thrust among the plural outboard motors.

Various modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this is not limited to the illustrative embodiments set forth herein. 

1. A control apparatus of multiple ship propellers controlling operation states of at least two ship propellers attached to a transom and transmitting and receiving operation information of the respective ship propellers mutually via a communication member, and configured to give a thrust difference between the ship propellers in the event of a fault of an electric rudder tilter used to turn a ship by turning a rudder by controlling thrusts of the respective ship propellers according to a detection value of a steering angle detector that detects a steering angle, wherein when a sailing direction of the ship is controlled by the thrust difference, the control apparatus controls the respective ship propellers by using a steering angle threshold up to which the thrust difference is not given between the ship propellers in a region in which the steering angle is small, and in a case where the steering angle exceeds the steering angle threshold, by using a predetermined value of the thrust difference with which the thrust difference is given between the ship propellers.
 2. The control apparatus of multiple ship propellers according to claim 1, wherein: magnitude of a thrust difference determined by the steering angle in a case where the thrust difference between the ship propellers is increased and magnitude of a thrust difference determined according to the steering angle in a case where the thrust difference is decreased are controlled to take different values.
 3. The control apparatus of multiple ship propellers according to claim 1, wherein: the thrust difference is given between the ship propellers so that a total thrust of all the ship propellers in the absence of a thrust difference and a total thrust of all the ship propellers after the thrust difference is given between the ship propellers are maintained equal.
 4. The control apparatus of multiple ship propellers according to claim 1, wherein: in a case where the thrust difference is given between the ship propellers, the thrust difference is given only by increasing a thrust, and in a case where the thrust difference between the ship propellers is eliminated, a thrust is deceased to one of a thrust before the thrust difference is given and a thrust of a ship propeller having a smallest thrust. 